Ammunition round with non-rigid attachment of projectile to cartridge case

ABSTRACT

A non-rigid connection is made between a non-metallic, combustible, cylindrical cartridge case body having a centrallyapertured domed front end and a projectile or shell having a concave outer annular portion engaging the domed front end and a threaded central attachment plug extending through the case aperture, by means of a locking ring threaded onto the plug to clamp the front end against the projectile and a thin annular spring washer having its inner periphery interposed between the ring and the inner periphery of the front end and its outer periphery engaging the front end outwardly of the ring.

Elite States atet Katz et a]. Sept. 3, 1974 [5 AMMUNITION ROUND WITH NON-RIGID 3,696,749 10/1972 Scanlon .I 102/010. 1 x ATTACHMENT 0}: PROJECTILE o 3,706,279 12/1972 Zimmerman [02/43 R CARTRIDGE CASE Inventors: Daniel Katz, Brooklyn, N.Y.; Peter H. Syben, Weaver, Ala.

The United States of America as represented by the Secretary of the Army, Washington, DC.

Filed: Jan. 17, 1973 Appl. No.: 324,267

Assignee:

US. Cl. 102/38, 102/43 R Int. Cl F42b 5/02 Field of Search l02/DIG. 1, 38, 40, 43 R,

References Cited UNITED STATES PATENTS Smith 102/38 Stadler 102/38 Larson l02/DIG. 1 X

Primary ExaminerSamuel W. Engle Assistant Examiner-H. J. Tudor Attorney, Agent, or FirmEdward J. Kelly; Herbert Berl; Thomas R. Webb 5 7 ABSTRACT A non-rigid connection is made between a nonmetallic, combustible, cylindrical cartridge case body having a centrally-apertured domed front end and a projectile or shell having a concave outer annular portion engaging the domed from, end anda threaded central attachment plug extending through the case aperture, by means of a loc lging ring threaded onto the plug to clamp the front end against the projectile and a thin annular spring washer having its inner periphery .interposed between the ring and the inner periphery of the front end and its outer periphery engaging the front end outwardly of the ring.

6 Claims, 4 Drawing Figures AMMUNITION ROUND WITH NON-RIGID ATTACHMENT OF PROJECTILE TO CARTRIDGE CASE BACKGROUND OF THE INVENTION In a conventional fixed artillery round (e.g., 152 mm) the domed front end of the cartridge case body is rigidly attached by epoxy resin to a corresponding concave annular surface on the base of the projectile. To provide additional reinforcement, the projectile base includes a central plug that extends through a central aperture in the domed end and a locking ring threaded onto the plug to clamp the inner periphery of the domed end to the projectile This attachment means, which has been used for over years, has the following disadvantages:

1. Due to the rigid epoxy bond between the case and the projectile, the rounds often fail to pass the present rigid drop test and pull strength requirements;

2. The epoxy resin used for bonding the case to the projectile prevents quick non-destructive separation of the case and projectile for re-working of mal-assembled ammunition and results in a costly increase in scrap;

3. The epoxy resin sometimes produces objectionable residue in the barrel of the weapon during fir- 4. The overall cost of assembly including the need for exhaustive quality control is excessive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a strong, reliable, non-rigid connection between a projectile and a non-metallic cartridge case body.

In accordance with the invention, a strong non-rigid connection is made between a non-metallic cartridge case body having an inwardly-extending front end with a central aperture and a projectile having an annular surface conforming to and engaging the case front end and a central attachment plug extending through the case aperture, by means of a locking ring threaded onto the plug and a thin annular spring washer having its inner periphery clamped between the ring and the inner periphery of the front end and its outer periphery engaging the front end outwardly of the locking ring. Preferably, the front end of the case body is curved in dome shape and the annular surface of the projectile is correspondingly shaped to fit the domed end. The spring washer may have an initial shape, prior to assembly and clamping, similar to the dome shape, or the washer may have an initial curvature greater than that of the domed case end, to cause the outer portion of the washer to resiliently engage the domed end after clamping.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a fixed round of ammunition in which the present invention is incorporated.

FIG. 2 is a sideview, partially cutaway in axial section, of the round of FIG. 1.

FIG. 3 is a transverse section view taken on line 3-3 of FIG. 2.

FIG. 4 is a view similar to FIG. 2, showing the parts in an intermediate stage of assembly.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT FIGS. 1-4 illustrate the invention as incorporated in a 152 mm fixed round of artillery ammunition, for example. As shown in FIGS. 1 and 2, the round 1 includes a projectile 3 attached to a non-metallic cartridge case 5. The case 5 comprises a hollow cylindrical body 7 formed with an inwardly-extending front end portion 9 of dome shape terminating in an inner peripheral region 10 which defines a central aperture 11. The case body 7 is normally made of combustible material, e. g.,

felted nitrocellulose, which supplements the propelling charge and is consumed during firing. The rear end of the case body 7 is closed by a flanged base 13, normally made of the same material as the body 7, attached to the body 7 by cement 15, e.g., of nitrocellulose lacquer. The case 5 contains one or more bags 17 of propellant adapted to be ignited by a primer 19.

The projectile 3, which would normally be a high explosive shell, comprises a cylindrical base 21 having a base 23 formed with an outer concave annular portion 25, which conforms in shape to and snugly engages the domed front end 9 of the case 7, and a central plug portion 27 which extends through aperture 1 1 and has external threads 29. A locking ring 31, threaded onto the plug portion 27, rigidly clamps the inner periphery 10 of the domed end 9 against surface 25 of the projectile. As shown in FIG. 2, the outer diameter of ring 31 substantially smaller than the outer diameter of the domed end 9 to avoid rigid clamping of the outer portion of the domed end 9 against surface 25. For example, the radial dimensions of the ring 31 and the domed end 9 may be 7 and 30 mm, respectively.

In order to increase the pull strength of the connection between the projectile and the case and also produce a non-rigid connection that can absorb the shock encountered in drop tests without damage to the round, a thin spring washer-33, having an inner diameter sub stantially the same as the locking ring 31, and an outer diameter nearly equal to that of the domed end 9, is interposed between the ring 31 and the domed end 9. For example, a washer having a radial dimension of 25 mm may be used with the examples given above for the ring 31 and domed end 9. The initial cross section shape of washer 33 (prior to clamping of the parts) may be substantially the same as the shape of the adjacent surface of the domed end 9, in which case the washer 33 supports, or resists forward movement of, the end 9 without resilient engagement therebetween. To provide resilient engagement, the washer 33 may have an initial curvature smaller than the curvature of the domed end 9, as shown in a partially-clamped stage of assembly in FIG. 4, where R, and R represent the radii of curvature of adjacent surfaces of the domed end 9 and washer 33, respectively, and R, R,. In order to provide a strong resilientconnection between the case and the projectile, the washer 33 must be made of a strong springy resilient material. The inner periphery 10 of the domed end 9 may be formed with cut-outs 35 leaving intermediate projections 37, for equalizing the gas pressure within the cartridge.

When a round of ammunition is dropped on a steel plate from a predetermined height, impact of either end with the plate exerts a bending force wherein the side of the connection opposite the point of impact is compressed and the same side of the connection tends to open up. With a conventional epoxy bond supplemented by a threaded connection without the spring washer in the 152 mm example given, the round generally failed at a drop height of about 2.5 feet and had a pull strength of only about 250 pounds. While the pulling force in the pull tests was exerted on the cartridge base 13, the cemented connection 15 was much stronger than the connection between the case and the projectile, so that the connection 15 never failed the pull tests. If the epoxy bond is omitted and the threaded connection without a washer is relied on, the connection is non-rigid, but is very weak, and fails to pass either the drop test or pull test requirements. On the other hand, rounds of ammunition of the 152 mm example incorporating the thin spring washer of the present invention consistently passed drop tests from 5 feet and pull tests of over 900 pounds, which constitute improvements of 100 and 260 percent respectively.

What is claimed is:

l. A round of ammunition including:

a. a cylindrical non-metallic cartridge case body comprising an inwardly-extending front end having a central aperture;

b. a generally cylindrical projectile having its rear end formed with an outer annular surface conforming to and engaging the exterior of said front end and a central attachment plug portion extending through said aperture;

c. a locking ring threaded onto said plug portion to clamp said front end against said annular surface of said projectile, the outer diameter of said ring being substantially smaller than that of said front end; and

d. a thin annular spring washer of strong springy material having its inner periphery clamped between said locking ring and. the inner periphery of said front end and its outer periphery larger than said locking ring and engaging said front end outwardly of said locking ring, to provide a strong resilient non-rigid connection between said cartridge case and said projectile.

2. A round as in claim 1, wherein substantially the entire front face of said washer is in contact with said front end.

3. A round as in claim 2, wherein the outer diameter of said washer is nearly equal to that of said front end.

4. A round as in claim 1, wherein said front end is domed.

5. A round as in claim 4, wherein the cross section shape of said washer prior to clamping is such that during assembly of the parts said outer periphery of said washer engages said domed end prior to engagement of said inner periphery with said front end, whereby said outer periphery resiliently engages said domed end after clamping.

6. A round as in claim 5, wherein said cross section shape prior to clamping is curved, with a curvature smaller than that of said domed end. 

1. A round of ammunition including: a. a cylindrical non-metallic cartridge case body comprising an inwardly-extending front end having a central aperture; b. a generally cylindrical projectile having its rear end formed with an outer annular surface conforming to and engaging the exterior of said front end and a central attachment plug portion extending through said aperture; c. a locking ring threaded onto said plug portion to clamp said front end against said annular surface of said projectile, the outer diameter of said ring being substantially smaller than that of said front end; and d. a thin annular spring washer of strong springy material having its inner periphery clamped between said locking ring and the inner periphery of said front end and its outer periphery larger than said locking ring and engaging said front end outwardly of said locking ring, to provide a strong resilient non-rigid connection between said cartridge case and said projectile.
 2. A round as in claim 1, wherein substantially the entire front face of said washer is in contact with said front end.
 3. A round as in claim 2, wherein the outer diameter of said washer is nearly equal to that of said front end.
 4. A round as in claim 1, wherein said front end is domed.
 5. A round as in claim 4, wherein the cross section shape of said washer prior to clamping is such that during assembly of the parts said outer periphery of said washer engages said domed end prior to engagement of said inner periphery with said front end, whereby said outer periphery resiliently engages said domed end after clamping.
 6. A round as in claim 5, wherein said cross section shape prior to clamping is curved, with a curvature smaller than that of said domed end. 